Well, it’s been a tough month for herbs since my last monthly soiree here at SBM.
Just last week at the American Society for Clinical Oncology (ASCO) meeting, a group out of the Mayo Clinic presented data from a study showing that a well-characterized flaxseed extract was ineffective against hot flashes in postmenopausal women. But as Steve Novella noted here earlier this week, negative clinical trials data on supplements rarely influence the behavior of those who continue to advocate for their herbal use.
Flaxseed, known to contain phytoestrogen compounds such as secoisolariciresinol diglucoside (SDG) and enterolactone, has been purported to relieve hot flashes.
But I think the hypothesis was flawed in the first place: while these compounds bind the estrogen receptor, they have largely been shown to be estrogen receptor modulators that act in a negative manner. Work from the group of Dr. Lillian Thompson at the University of Toronto has repeatedly shown in an estrogen-dependent animal model of human breast cancer that flaxseed components act in a predominantly anti-estrogenic manner. One might suspect that hot flashes would be made worse by flaxseed, although this was not the case in the study presented as ASCO.